Detecting Intracluster Gas Motion in Galaxy Clusters: Mock Astro-E2 Observations

We explore the detectability of bulk motions in the X-ray emitting intracluster medium (ICM) using a catalog of 1,836 mock Astro-E2 observations of simulated clusters of galaxies. We generate high resolution mock spectra for two observing strategies: a four-pointing mosaic and a single central pointing. Normalizing to 200 (400) photons in the iron K-alpha region for the mosaic (central) study, we fit Poisson realizations of each simulated spectrum to a velocity broadened isothermal plasma emission model. We confirm that the velocity characteristics (mean and dispersion) returned by the spectral fittings are unbiased measures of the emission-weighted values within the observed region, with scatter 55 km/s. The maximum velocity difference between mosaic element pairs $\Delta v_{\rm max}$ has ~ 6% likelihood of being transonic ($\Delta v_{\rm max} \ge 0.5 c_s$), and the likelihood falls steeply, p \spropto (\Delta v_{\rm max}/c_s)^{-4}, at high Mach number. The velocity broadening parameter $\sigma_v$ from the central pointing fit exceeds the thermal value in 49% of the cases, with again a $\sigma_v^{-4}$ tail at large dispersion. We present as case studies the clusters that yield the strongest signal for each observing strategy.Comment: 13 pages, 20 figures. Submitted to ApJ. Version with postscript figures embedded in the text available at http://www.umich.edu/~apawl/astroe2/. Version 2 includes changes in response to referee report and corrects an error in optical depth estimate

Simulation-Based Resuscitative Transesophageal Echocardiography Training for Emergency Medicine Residents

Introduction: Resuscitative TEE is an emerging tool in the cardiac arrest tool-box, and can improve outcomes in OHCA. • Identifies reversible causes • Decreases time off chest • Evaluates compression efficacy • Improves assessment during pulse-checks • Simulation training can prepare EM residents to obtain and interpret TEE views on a live patient.https://knowledgeconnection.mainehealth.org/lambrew-retreat-2023/1008/thumbnail.jp

Systematic Evaluation of GPT-3 for Zero-Shot Personality Estimation

Very large language models (LLMs) perform extremely well on a spectrum of NLP tasks in a zero-shot setting. However, little is known about their performance on human-level NLP problems which rely on understanding psychological concepts, such as assessing personality traits. In this work, we investigate the zero-shot ability of GPT-3 to estimate the Big 5 personality traits from users' social media posts. Through a set of systematic experiments, we find that zero-shot GPT-3 performance is somewhat close to an existing pre-trained SotA for broad classification upon injecting knowledge about the trait in the prompts. However, when prompted to provide fine-grained classification, its performance drops to close to a simple most frequent class (MFC) baseline. We further analyze where GPT-3 performs better, as well as worse, than a pretrained lexical model, illustrating systematic errors that suggest ways to improve LLMs on human-level NLP tasks.Comment: Short Paper (5 pages), Accepted to (WASSA) 13th Workshop on Computational Approaches to Subjectivity, Sentiment & Social Media Analysis at ACL 202

The Distance to NGC 2264

We determine the distance to the open cluster NGC 2264 using a statistical analysis of cluster member inclinations. We derive distance-dependent values of sin i (where i is the inclination angle) for 97 stars in NGC 2264 from the rotation periods, luminosities, effective temperatures, and projected equatorial rotation velocities, v sin i, measured for these stars. We have measured 96 of the v sin i values in our sample by analyzing high-resolution spectra with a cross-correlation technique. We model the observed distribution of sin i for the cluster by assuming that member stars have random axial orientations and by adopting prescriptions for the measurement errors in our sample. By adjusting the distance assumed in the observed sin i distribution until it matches the modeled distribution, we obtain a best-fit distance for the cluster. We find the data to be consistent with a distance to NGC 2264 of 913 pc. Quantitative tests of our analysis reveals uncertainties of 40 and 110 pc due to sampling and systematic effects, respectively. This distance estimate suggests a revised age for the cluster of 1.5 Myrs, although more detailed investigations of the full cluster membership are required to draw strong conclusions.Comment: 12 pages, 11 figure

THE POTENTIAL EFFECT OF MINI-TRAMPOLINE STIFFNESS ON TAKE-OFF BEHAVIOUR OF GYMNASTS – A METHODOLOGICAL STUDY

The purpose of this study was to compare two mini-trampolines with different spring constant in regard to their effect on take-off mechanics. It was expected that the softer (36 springs) trampoline would lead to a longer contact time and a higher take-off impulse. To assess reaction forces during jumps a flexible force insole was used simultaneously with the measurement of run-in velocity by timing gates. Results showed no significant differences in contact mechanics or contact time indicating that the difference between these two trampolines is only marginal. Therefore, this study provides mainly a novel measurement approach to assess the effect of equipment changes in trampolining. Future studies are warranted to assess the athlete-equipment interaction in greater detail